Explore the evolution and best practices of product requirements documents (PRDs). PRDs are powerful and important tools used by various companies in the software industry. They serve as a log of a product concept's scope and objectives and allow for effective communication and collaboration across different teams. PRDs should be adaptable, measurable, and comprehensive, catering to the needs of different stakeholders. Templates and formats can vary, but the key is to capture the why, how, and what of a product in a way that is concise and easily understood. PRDs can provide value and alignment throughout the product development process.